Definition of mesocarp in English:

noun

The fruit is a one-seeded drupe consisting of a fleshy exocarp and mesocarp and a hard endocarp that is united with the seed coat.

In peach fruit, cell numbers in the mesocarp and endocarp appear to be fixed several weeks after full bloom, and subsequent growth of the fruit is exclusively supported by cell enlargement and formation of intercellular spaces.

In part, the large mesocarp of ripe fruits can be viewed as a necessary cost to the plant to facilitate caching behavior by the rodent.